Your sport utility vehicle making a worrisome rattle? Who you gonna call now?

Declaring it “time to stop and smell the cappuccino,’’ Tom and Ray Magliozzi, cohosts of the long-running public radio show “Car Talk,’’ informed fans Friday via the show’s website that they will stop producing new programs this year, beginning in October.

Produced at Boston’s WBUR-FM, where it debuted in 1977, “Car Talk’’ celebrates its 25th anniversary as a national broadcast this fall. The show, which combines practical advice on car selection and maintenance with wry social commentary and self-deprecating brotherly humor, will live on in syndication, but in repackaged form. Future shows will draw upon segments from the more than 1,200 episodes in its archives.

TED DULLY/GLOBE STAFF/FILE

Ray (left) and Tom Magliozzi in 1983 outside the Good News Garage in Cambridge, which is still owned and operated by Ray.

Known for their cackling laughs and by their radio personae “Click and Clack: The Tappet Brothers,’’ the Magliozzis will keep writing their weekly “Dear Tom and Ray’’ column. Tom’s upcoming 75th birthday was the main reason cited in the retirement announcement, a scenario confirmed by Doug Berman, the show’s executive producer.

“When they decided it was time, Tom was probably more ready than Ray was,’’ Berman said Friday. “But they consider themselves a team, and they like the [syndication] plan that’s now in place.’’

Berman said ratings for repeats of “Car Talk’’ have rivaled those for new programs. Heard on more than 660 stations, “Car Talk’’ reaches an average weekly audience of about 3.3 million. Neither Magliozzi brother returned calls seeking comment on the decision.

Plenty of the show’s fans had something to say, though. Loyal listener Joerama Valianti of Gloucester heard the news on WBUR and quickly called the station to confirm it.

“I’m kind of sad about it, and a bit in shock, really,’’ Valianti said Friday. “They’ve kept me company and made me laugh for 15 to 20 years. They both seem so young, too, at least in spirit.’’

Social media and blog sites buzzed with reaction to the announcement. Peter Sagal, host of the NPR quiz show “Wait Wait, Don’t Tell Me,’’ tweeted that the most important lesson he had learned from “Car Talk’’ was that “people listen to you on the radio forever, if they like you. Kindness [is greater than] clever.’’

At WBUR, where “Car Talk’’ is second (behind “Wait Wait’’) in weekly listenership, the station’s answering service was flooded with calls. What has made “Car Talk’’ so distinctive, according to Sam Fleming, WBUR managing director of news and programming, is its appeal to nonregular NPR listeners, many of whom live in areas of the country where public radio is disdained as elitist.

“People feel like these are such regular guys,’’ said Fleming, adding, “For us at ’BUR, the saddest thing will be not having them around the building so much. The fun they have together is infectious.’’

At the Good News Garage in Cambridge, owned and managed by Ray Magliozzi, 63, there was scant evidence of fans dropping by to mourn the news. Technician Tim Neves said his boss had barely mentioned the announcement Friday morning while he was at the garage, where there is no obvious signage connecting the humdrum garage to the wildly popular radio show.

While “Car Talk’’ fans come by regularly, said Neves, with the news just trickling out, none had shown up, unless a repair job was at issue. “Ray’s pretty low-key anyway, and he keeps the garage and show separate,’’ added Neves.

“Car Talk’’ went national in 1987, picked up by NPR as part of its “Weekend Edition’’ package. It has since grown into a pop culture phenomenon, spawning an animated PBS series (“Click and Clack’s As The Wrench Turns’’), theatrical adaptation (“Car Talk: The Musical’’), and show-themed product line (clothing, coffee mugs, music CDs). In 1992, the show’s production team formed a no-kidding firm called Dewey, Cheetham & Howe (say it fast to get the joke), whose offices are in Harvard Square.

Each weekly show features roughly a dozen usually clueless callers sharing tales of balky transmissions and misfiring spark plugs. When not dispensing helpful advice, the hosts banter and often bicker, making fun of everyone and everything from vegetarians to cat lovers to Camaro drivers.

In a 2005 Globe interview, Ray Magliozzi said, “What we do may be in bad taste, but it’s rarely mean. We’re not shock jocks. We’re usually laughing at ourselves.’’

On their website, cartalk.com, the brothers counseled fans not to mope. “We’ve managed to avoid getting thrown off NPR for 25 years,’’ noted Ray with characteristic cheeriness, “given out tens of thousands of wrong answers, generated lawsuit threats from innumerable car companies, and had a hell of a lot of fun talking to you guys.’’

Asked how long the decision had been brewing, Berman laughed. “It’s been in the works for 24 years,’’ he said.

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